In a current professional wireless communication system, a communication distance of a terminal is limited. In the case where the terminal is out of coverage of a transmitter terminal or at the edge of a valid area, a situation of a weak signal or no signal occurs, thus the quality of a call is very bad or a call can not even be established. Under the circumstance, a repeater is needed to amplify and forward the signal, to enlarge the communication range and ensure the stability and reliability of communications.
A repeater is basically configured to forward a received signal by a transmitter of its own, and required to operate in accordance with a prescriptive forwarding protocol to achieve a forwarding function. And a major feature thereof is that it can effectively enlarge the communication range and capability of a handset, a vehicle station and a fixed station in a communication system, providing a larger coverage radius for the system.
An ordinary repeater includes units of a receiver, a transmitter, a duplexer, a power divider and an antenna feeder. Such devices usually operate in an unattended state, some of them are placed on a high mountain with bad operating environment and some of the devices are sometimes kept in a transmitting state for a very long time. Thus, the technical design requirement of a repeater is much higher than that of a handhold terminal or a vehicle-station, and there are even some special requirements, such as a high stability, a high reliability, excellent heat dissipation and a longtime stable operation at a high temperature or a low temperature. Therefore, an ordinary repeater usually has a very large volume, a bad movability and a high cost, and is unsuitable to be applied in a complex and changeable conventional system.